The present invention relates to a light beam scanning apparatus using a hologram rotator, particularly to a light beam scanning apparatus wherein the deviation of the scanning position of the scanning beam due to the mode hopping of the laser diode as a light source is corrected, whereby an improved linear scanning and a high focusing degree of the light beam can be attained.
Recent research and development has enhanced the operations of a laser printer using holography, in which the laser printer produces an image by scanning the laser light beam on the scanning plane through a polygon mirror and lens system. Other developments include low cost light beam scanning apparatuses using a hologram scanner provided with a hologram disk instead of the polygon mirror and lens system. Laser printers including the hologram scanner have fewer problems when utilizing a gas, e.g., He-Ne, laser or the like, than, for example, those using a laser diode, wherein the deviation of the scanning position of the light beam occurs due to mode hopping of the laser diode. Thereby, an apparatus using a hologram scanner is prevented from obtaining a satisfactory performance. Also, the linearity of the scanning beam (uniform velocity characteristic of the scanning beam with respect to the uniform angular velocity of the hologram disk), and the image focusing characteristics of the scanning beam without optical lenses, are not completely satisfactory.